This invention relates to a single or multiple-plate flat metal sealing gasket, particularly a cylinder head gasket or a sealing gasket for a flange of an exhaust pipe in internal-combustion engines. The sealing gasket has at least one beaded spring steel plate as a sealing layer as well as overlays of pressure-resistant material provided on at least one of the metal plates for obtaining a high sealing pressure in the region of the gasket apertures.
It is known to make cylinder head gaskets for internal-combustion engines using a single-layer sheet metal or multi-layer sheet metal laminates. For increasing the sealing effect particularly around the gasket apertures which surround the combustion chambers, but also around gasket apertures which surround the liquid passages for the lubricant and coolant as well as apertures for the passage of bolts, it is known to provide the metal plates with embossed beads which surround the gasket apertures. In gaskets formed of sheet metal laminates either all or only some of the metal plates (laminae) may be provided with beads. For obtaining an improved elastic deformation resistance of the beads, at least one of the sheet metal plates is formed of a spring steel while for the other sheet metal plates other types of steel or metal alloys may be used which, if required, may have different mechanical properties.
European Patent No. 0 486 817 discloses a cylinder head gasket formed of a beaded sealing plate having an annular metal compensating disk which is situated on the upper face of the sealing plate and is welded thereto. The beads of the sealing plate are made of spring steel to ensure that they have a substantial elastic resistance to deformation.
When the overlays are welded to the sealing plates according to the prior art, risks are high that the elastic properties of the beads are adversely affected by temperatures prevailing during welding.